powerpc/64s: Avoid saving faulting address into EX_DAR in SLB miss

The EX_DAR save area is only used in exceptional cases. With r3 no
longer clobbered by slb_allocate_realmode, saving faulting address to
EX_DAR can be deferred to those cases.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 64365907cddc577708a17a7b71254dbf49421ed9..fe3bc52aadf88f42e7b0d648295c82091a3772fb 100644 (file)
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -631,7 +631,6 @@ EXC_COMMON_BEGIN(slb_miss_realmode)
 
        stw     r9,PACA_EXSLB+EX_CCR(r13)       /* save CR in exc. frame */
        std     r10,PACA_EXSLB+EX_LR(r13)       /* save LR */
-       std     r3,PACA_EXSLB+EX_DAR(r13)
 
        crset   4*cr0+eq
 #ifdef CONFIG_PPC_STD_MMU_64
@@ -641,11 +640,10 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
 #endif
 
        ld      r10,PACA_EXSLB+EX_LR(r13)
-       ld      r3,PACA_EXSLB+EX_R3(r13)
        lwz     r9,PACA_EXSLB+EX_CCR(r13)       /* get saved CR */
        mtlr    r10
 
-       beq     8f              /* if bad address, make full stack frame */
+       beq-    8f              /* if bad address, make full stack frame */
 
        andi.   r10,r12,MSR_RI  /* check for unrecoverable exception */
        beq-    2f
@@ -660,6 +658,7 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
 .machine       pop
 
        RESTORE_PPR_PACA(PACA_EXSLB, r9)
+       ld      r3,PACA_EXSLB+EX_R3(r13)
        ld      r9,PACA_EXSLB+EX_R9(r13)
        ld      r10,PACA_EXSLB+EX_R10(r13)
        ld      r11,PACA_EXSLB+EX_R11(r13)
@@ -668,7 +667,9 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
        rfid
        b       .       /* prevent speculative execution */
 
-2:     mfspr   r11,SPRN_SRR0
+2:     std     r3,PACA_EXSLB+EX_DAR(r13)
+       ld      r3,PACA_EXSLB+EX_R3(r13)
+       mfspr   r11,SPRN_SRR0
        LOAD_HANDLER(r10,unrecov_slb)
        mtspr   SPRN_SRR0,r10
        ld      r10,PACAKMSR(r13)
@@ -676,7 +677,9 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX)
        rfid
        b       .
 
-8:     mfspr   r11,SPRN_SRR0
+8:     std     r3,PACA_EXSLB+EX_DAR(r13)
+       ld      r3,PACA_EXSLB+EX_R3(r13)
+       mfspr   r11,SPRN_SRR0
        LOAD_HANDLER(r10,bad_addr_slb)
        mtspr   SPRN_SRR0,r10
        ld      r10,PACAKMSR(r13)